Simulated desert varnish products and methods of making same

ABSTRACT

The disclosure relates to a composition of matter comprising a rock substrate having a coating simulating natural desert varnish which can be developed within a few days, as contrasted to natural desert varnish which requires at least decades to develop in nature. The coating comprises an initial layer of the reaction product of the rock substrate with a solution of an alkali base and a finishing cover comprising the reaction product of the initial layer with a solution of a metallic salt. Optionally, the coating can include an additional covering of sodium hypochlorite.

This application is a division of copending application Ser. No. 828,142filed 02/07/86, now U.S. Pat. No. 4,725,451, which is a continuation ofapplication Ser. No. 06/762,794 filed 08/02/85, now abandoned, which isa continuation of Ser. No. 06/689,501, filed 01/08/85, now abandoned,which is a continuation of Ser. No. 06/598,394, filed 04/09/84, nowabandoned, which is a continuation of application Ser. No. 06/517,468filed 07/26/83, now abandoned, which is a continuation of applicationSer. No. 06/418,556 filed 09/15/82, now abandoned, which is acontinuation of Ser. No. 06/071,506, filed 08/31/79, now abandoned,which is a continuation of Ser. No. 05/865,455 filed 12/29/77, nowabandoned, each continuation having been copending with each predecessorapplication.

BACKGROUND OF THE INVENTION

This invention is a method of simulating in a very short time the desertvarnish produced by nature over decades and longer periods of time. Theinvention further relates to articles of manufacture simulating thesurface appearance of natural desert varnish.

Much of the desert areas, both valleys and mountains, found in arid andsemi-arid regions of the United States and other parts of the world arecovered by a thin coating of generally dark coloration. For example, inthe Southern California and Arizona deserts the varnish coversseventy-five percent (75%) of the coherent-stable rock surface includingmountain ranges. In some areas of Southern California it has beendemonstrated that desert varnish may be formed within twenty-five yearsafter exposure of fresh rock. However, in other areas, such as Arizona,petroglyphs documented to have been formed four hundred to a thousandyears ago by scraping away desert varnish coatings have not been coveredby the re-establishment of the desert varnish. In Egypt desert varnishis barely perceptible on pyramids that have existed for 5,000 yearssince construction.

In desert areas man's activities, such as the construction of dams,roads, preparation of sites for construction and other activities of alike nature have exposed large, unsightly areas of lightly coloredglaring scarps of freshly exposed rock which are visible from greatdistances as unsightly anomalies on the desert landscape. The removal ofthe natural desert varnish in this fashion occurs in both urban andrural areas and is particularly objectionable in the highly visiblemountain areas; for example, where large cuts and fills are made toaccommodate building sites.

Nature's timetable in restoring the desert varnish to the freshlyexposed rock is much too long; therefore, a desire and need for a methodand/or product to be used in restoring the natural desert varnish orcovering the exposed areas with articles of manufacture simulatingdesert varnish coated natural rock constitutes a longstanding,unfulfilled need.

BRIEF DESCRIPTION OF THE INVENTION

Briefly, the present invention provides as compositions of matter asuitable rock substrate having a coating of the reaction product of asoluble basic salt, suitably an alkali, preferably sodium hydroxide andpotassium hydroxide, and a soluble metallic salt, suitably a solublesalt of manganese or iron, preferably manganese chloride, manganesenitrate, iron chloride, or iron sulfate (the hydrates thereof areintended to be included). In its broader aspect, the composition of thecoating may contain a ratio of such basic to metallic salts betweenabout 1:80 to about 100:1. A preferred ratio of basic to metallic saltsin the composition of the coating is about 1:1.

In another aspect, the invention is the method of producing an articleof manufacture which simulates natural desert varnish on a suitable rocksubstrate which embraces the steps of applying to the rock, in order:

(1) An effective amount of a solution of soluble basic salts, e.g.,alkali salts such as sodium hydroxide and potassium hydroxide, and

(2) An effective amount of a solution of soluble metallic salts of ironor manganese, preferably manganese chloride, manganese nitrate, ironchloride and iron sulfate and, in an alternative embodiment, theapplication of the soluble metallic salts may be followed by anapplication of an effective amount of sodium hypochlorite.

The concentrations of alkali and metallic salts solutions may be fromabout 0.05N to about 5N and from about 0.05N to about 4N, respectively,and the ratios of alkali to metallic salts solutions range from about1:80 to about 100:1; the preferred ratio being about 1:1.

The process may be effectively practiced by applying the alkali andmetallic salts solutions to the rock substrate at a coverage rate ofabout 0.5 cc per square foot to about 25 cc per square foot, a preferredrate of application being 6 cc per square foot. The upper limit may beextended for porous rock types to 100 cc per square foot.

An additional step which in some instances proves effective, is theapplication of a solution of sodium hypochlorite which may be from about0.05N to about 5N, preferably from about 0.5N to about 1.5N, and mostpreferred about 0.75N, in a ratio to the metallic salts of about 1:1with a coverage of about 6 cc per square foot.

A suitable rock substrate treated according to the teachings of thisinvention may be expected to develop initial color in about one day,full color in about one week, and a patina resembling closely theancient, natural desert varnish, in about six to seven months.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Further understanding of the invention may be gained from aconsideration of the following examples and comments:

EXAMPLE I

Approximately fifty square feet of freshly exposed (no desert varnishformed since disturbed) granite rock was treated according to theteachings of this invention as follows: The test area was sprayed with a1N solution of KOH by means of a portable hand-pressurized gardensprayer. The coverage was approximately 6 cc per square foot. Withinfive to ten minutes after the initial application of KOH solution a 1Nsolution of MnCl₂ was applied at the rate of 6 cc per square foot.

An intense black coating resulted from the treatment in one week. Withinseven months after the treatment a dull, greasy patina resemblingnaturally occurring desert varnish developed on the treated site.

EXAMPLE II

The protocol of Example I was followed on approximately fifty squarefeet of freshly exposed granite rock with the additional step oftreating the test area with an application of 1N FeCl₂ within five toten minutes after the application of the 1N manganese chloride.

A black coating with brown highlights resulted from the treatment.Within seven months after the treatment a dull, greasy patina resemblingnaturally occurring desert varnish developed on the treated site.

EXAMPLE III

Approximately two hundred fifty square feet of freshly exposed schistsituated as a vertical scar on a mountain side was treated according tothe teachings of this invention as follows:

The test area was sprayed with a 1N solution of potassium hydroxide bymeans of a portable pressurized garden sprayer. Within minutes after thefirst application of potassium hydroxide an application of one normalMnCl₂ was made. Both applications were applied at the rate of 6 cc persquare foot.

The site was examined periodically and it was noted that a patinaresembling that of naturally occurring desert varnish developed withinseven months after the treatment. No bleeding or transportation of thestaining has since occurred.

EXAMPLE IV

Approximately one thousand square feed of schist (with pronounced whitetalc deposits) disposed as a vertical scar on a mountain side, weretreated according to the teachings of this invention as follows:

A solution of one normal KOH was applied at the rate of 6 cc per squarefoot. Within twenty minutes after the first application a one normalsolution of Mn(NO₃)₂ was applied to the area at the rate of 6 cc persquare foot. Thereafter, within thirty minutes of the second applicationone hundred square feet of the area was treated with an additionalapplication of one normal solution of Fe₂ (SO₄)₃ at the rate of 6 cc persquare foot.

The result was an intense black coating over the treated area exceptwhere treated with Fe₂ (SO₄)₃ which resulted in brown highlighting.

EXAMPLE V

Approximately three hundred square feet of schist was treated with a onenormal solution of potassium hydroxide followed by a 0.5 normal solutionof Mn(NO₃)₂ applied within thirty minutes after the application of theKOH according to the protocol of Example I.

The application resulted in a pleasing black coating which closelymatched the surrounding rock.

EXAMPLE VI

Approximately ten thousand square feet of phyllite was treated accordingto the teachings of this invention as follows:

A one normal solution of KOH followed by Mn(NO₃)₂ solution,approximately 0.25N to 0.5N was applied to the test area at varyingtimes between fifteen minutes and two days at a rate of approximately 6cc per square foot. Approximately one week after the second application,a one normal solution of Fe(SO₄)₃ was applied to random sites in thetest area.

The result was a variegated black coating with golden brown highlightsin Fe₂ (SO₄)₃ treated areas. One day after the completion of the processalmost an inch of rain fell on the test site, but no bleeding of stainoccurred.

EXAMPLE VII

Approximately nine hundred square feet of phyllite rock was treatedaccording to the teachings of this invention, as follows:

A 1N solution of KOH was applied to the substrate at the rate of 6 ccper square foot, followed by an application of 1N manganese nitrateapplied at the rate of approximately 3 cc per square foot.

Within 45 minutes after the application of MnNO₃ a 1N solution of Fe₂(SO₄)₃ was applied at the rate of approximately 3 cc per square foot.The resulting color was predominately reddish-brown with variegatedblack coloration.

EXAMPLE VIII

Approximately two hundred square feet of phyllite substrate was treatedaccording to the teachings of this invention as follows:

A 1N KOH solution was applied to the substrate with a coverage ofapproximately 6 cc per square foot. Within 15 minutes an application of1N (Mn(NO₃)₂ to the substrate was made with a coverage of approximately10 cc per square foot, resulting in intense black coloration.

In all of the examples above, color began to develop within twenty-fourhours after completion of treatment and reached full intensity withinseven days. In each case a patina developed, presenting an appearancealmost indistinguishable from natural desert varnish, in about seventhmonths after the treatment.

The process of this invention has been found effective on a variety ofigneous, metamorphic and sedimentary rocks including: basalt, andesite,rhyolite, diorite, gabbro, metarhyolite, quartzite, phyllite, schist,gneiss, hornfels, sandstone, conglomerate, graywacke, chert and impurecarbonates. On the other hand, readily soluble and unstable rock such aspure limestone and dolomites will not maintain the surface. Friablesedimentary rocks and unstable slopes will take, but not support, thecoatings due to abrasion from movement and dislocation.

The initial application of the alkali should be a concentration of atleast about 0.1N, and the practical maximum is 5N. A preferred range ofconcentrations of the alkali solution is from 0.05N to 5N.

Good results are obtained with ratios of alkali to manganese salts andiron from about 1:10 to about 20:1. A preferred range of ratios is fromabout 1:2 to about 5:1 and the most preferred is a 1:1 ratio.

Preferred alkalis are KOH and NaOH; the preferred manganese salts arethe chlorides and nitrates, and the preferred iron salts are thechlorides and sulfates.

The use of manganese concentrations of about 0.05N furnish barelyperceptible black staining, whereas at the other extreme manganeseconcentrations about 4N to 5N produce intensely colored black.

1N solutions of both base and manganese applied in a 1:1 ratio provide ablack intense equal to the most intense black normally found in naturaldesert varnish.

Similar concentrations of iron salts produce reddish hues.

Although the inventor does not wish to be bound by the theory, it isthought that the application of the alkali followed by the manganese oriron salt oxidizes the metallic salt which is further oxidized veryquickly be exposure to air. The chemical reaction which occurs probablymay be represented as follows:

    Mn(NO.sub.3).sub.2.xH.sub.2 O+H.sub.2 O+KOH⃡Mn(OH).sub.2 (brownish white ppt)

    Mn(OH).sub.2 .sub.O.sbsb.2 air⃡MnO.sub.2 (black oxide ppt.)

    2Mn.sup.+3 +2H.sub.2 O⃡Mn.sup.++ +MnO.sub.2 +4H.sup.+ (black oxide ppt)

    FeCl.sub.2 +OH⃡Fe(OH).sub.2 (white ppt)

    Fe(OH).sub.2 +H.sub.2 O⃡air.sub.O.sbsb.2 Fe.sub.2 O.sub.3 ·xH.sub.2 O (golden brown/rusty ppt)

In a limited application, soluble alkali and manganese salts may bemixed at concentrations of 0.1N or less and sprayed on together. Theresult is less satisfactory than using higher concentrations seriatim.

The time limitations between applications of alkali and manganese saltsappears to be limited only by factors that remove the alkali, e.g.,rain.

The application of sodium hypochlorite following the application of ametallic salt solution in the process described herein will speed up theprocess significantly. However, if both manganese and iron salts arepresent, only the iron precipitate and no manganese precipitant isformed.

A number of specific examples of the preferred embodiments of thepractice of this invention has been set forth above, and from theteachings of this disclosure persons ordinarily skilled in the art willappreciate that other and different embodiments may be devised withoutundue experimentation, all of which are within the spirit and scope ofthis disclosure and the invention covered thereby. For example, althoughthe preferred embodiment of the process at present contemplates theapplication of the chemicals to the substrate by spraying, other methodsof applying the chemicals may be used, such as, brushing, dipping, andthe like.

All such equivalent variations and modifications are intended to beincluded within the scope of this invention as exemplified by theappended claims.

What is claimed is:
 1. A composition of matter comprising a stable,insoluble rock substrate having a coating applied to a scarred surfacethereof, said coating comprising an initial layer of the reactionproduct of said rock with a 0.05N to 5N solution of alkali bases and afinishing cover comprising the reaction product of said initial layerwith a 0.05N to 4N solution of metallic salts selected from the salts ofiron and manganese.
 2. The composition of claim 1 wherein said alkalibases are selected from NaOH and KOH, and said metallic salts areselected from MnCl₂, Mn(NO₃)₂, FeCl₂ and Fe₂ (SO₄)₃.
 3. The compositionof claim 1 wherein the ratio, by weight, of alkali to metallic salts isabout 1:80 to about 100:1.
 4. The composition of claim 1 wherein theratio of alkali to metallic salts is about 1:1.
 5. The composition ofclaim 1 including a covering layer of sodium hypochlorite.
 6. Thecomposition of claim 1 wherein the concentrations of the alkali andmetallic salt solutions are from about 0.5N to 1N each.
 7. Thecomposition of claim 1 wherein the concentration of the alkali solutionis about 1N and the concentration of the metallic salt solution is about1N.
 8. The composition of claim 1 wherein the ratio, by weight, ofalkali to metallic salts is about 1:16 to about 30:1.